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Journal articles on the topic 'Coaxial jet'

Author: Grafiati

Published: 4 June 2021

Last updated: 22 February 2023

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1

Kozlov, V. V., G. R. Grek, M. V. Litvinenko, Yu A. Litvinenko, A. S. Tambovtsev, and A. G. Shmakov. "Features of the Round Hydrogen Microjet Combustion in a Coaxial Jet of the Air and Nanopouder Mixture." Siberian Journal of Physics 14, no. 2 (2019): 35–45. http://dx.doi.org/10.25205/2541-9447-2019-14-2-35-45.

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Results of the experimental studies of a round hydrogen microjet combustion in a coaxinal jet of air and SiO2 nanopouder mixture efflux from a slot-hole (multinozzle) coaxial nozzle at subsonic and supersonic efflux velocity are presented. It is shown that scenarios of a hydrogen microjet combustion in a coaxinal jet of air and nanopouder mixture are similar to scenarios of diffusion combustion of a hydrogen microjet at subsonic and supersonic efflux velocity. Existence of “bottleneck flame region” is revealed at subsonic and a flame separation from a nozzle exit at supersonic efflux velocity. It is found that with efflux velocity growth of jets it is possible to observe intensification of the luminescence of the flame at the boundary between the jet of hydrogen and air / nanopowder mixture and existence of «bottleneck flame region» as in a laminar coaxial jet and in a flame of a hydrogen microjet combustion. On the other hand, it is possible to observe actually disappearance of the «bottleneck flame region» at approach to transonic efflux velocity.

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2

Kozlov, V. V., G. R. Grek, M. V. Litvinenko, Yu A. Litvinenko, A. S. Tambovzev, and A. G. Shmakov. "Air Round Microjet Interaction with Coaxial Hydrogen Jet at It Combustion for Supersonic Speed Jets Efflux." Siberian Journal of Physics 14, no. 3 (2019): 53–63. http://dx.doi.org/10.25205/2541-9447-2019-14-3-53-63.

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Results of experimental studies of the round air microjet interaction with a coaxial hydrogen jet at its combustion for supersonic speed jets efflux are presented in this work. It is revealed that combustion of the coaxial hydrogen jet with growth of its speed efflux is accompanied by all scenarios, observed at study of the round and plane hydrogen microjets diffusion combustion. However, “bottleneck flame region” undergoes considerable geometrical deformations because of specifics of a flame of a coaxial jet. It is shown that “bottleneck flame region” is transformed from Y-shaped to spherical shape in the activity of growth of a coaxial jet speed efflux. It is found that a round air microjet interaction with a coaxial hydrogen jet at its combustion is accompanied by several new phenomena: existence of cone-shaped area a coaxial jet combustion near a nozzle exit; existence of small-scale supersonic cells on a resultant flame; absence of the hydrogen combustion efflux from combustion region of a coaxial jet near nozzle exit; flame-out from combustion region of a coaxial jet near nozzle exit that leads to hydrogen ignition downstream, its intensive combustion and sharp acoustic noise occurrence; existence of a turbulent flame, to its separation from a nozzle exit and transition to supersonic combustion of a resultant jet.

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3

Kozlov, V. V., G. R. Grek, M. M. Katasonov, M. V. Litvinenko, Yu A. Litvinenko, A. S. Tambovtsev, and A. G. Shmakov. "Features of the Round Hydrogen Microjet Combustion in a Coaxial Air Jet." Siberian Journal of Physics 14, no. 2 (2019): 21–34. http://dx.doi.org/10.25205/2541-9447-2019-14-2-21-34.

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Results of experimental studies of features of the round hydrogen microjet combustion in a coaxial air jet are presented in this work. It is shown that the combustion scenario is connected with existence of the «bottleneck flame region». This fact correlates with the similar scenarios of the diffusion hydrogen microjet combustion at subsonic efflux velocity investigated by us earlier. It is revealed that the spherical shape of the “bottleneck flame region” is transformed to a cylindrical shape. It is found that the round hydrogen microjet combustion in a coaxial air jet at supersonic efflux velocity is accompanied by existence of supersonic cells both in a hydrogen microjet and in a wake of coaxial air jet. Round hydrogen microjet supersonic combustion in a coaxial air jet is connected with a flame separation from a nozzle exit.

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4

Abrosimov, I. A., A. M. Turilov, and V. A. Kosterin. "Control of coaxial jet mixing." Russian Aeronautics (Iz VUZ) 50, no. 1 (March 2007): 98–100. http://dx.doi.org/10.3103/s1068799807010175.

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5

Belkacem, Safer Nabil, and Beghidja Abdelhadi. "MIXING IN TURBULENT COAXIAL JET." Journal of Mechanical Engineering Research and Developments 42, no. 3 (May 24, 2019): 110–19. http://dx.doi.org/10.26480/jmerd.03.2019.110.119.

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6

van Hout, René, Sudharson Murugan, Abhijit Mitra, and Beni Cukurel. "Coaxial Circular Jets—A Review." Fluids 6, no. 4 (April 8, 2021): 147. http://dx.doi.org/10.3390/fluids6040147.

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This review article focuses on the near-field flow characteristics of coaxial circular jets that, despite their common usage in combustion processes, are still not well understood. In particular, changes in outer to inner jet velocity ratios, ru, absolute jet exit velocities and the nozzle dimensions and geometry have a profound effect on the near-field flow that is characterized by shear as well as wake instabilities. This review starts by presenting the set of equations governing the flow field and, in particular, the importance of the Reynolds stress distributions on the static pressure distribution is emphasized. Next, the literature that has led to the current stage of knowledge on coaxial jet flows is presented. Based on this literature review, several regions in the near-field (based on ru) are identified in which the inner mixing layer is either governed by shear or wake instabilities. The latter become dominant when ru≈1. For coaxial jets issued into a quiescent surrounding, shear instabilities of the annular (outer) jet are always present and ultimately govern the flow field in the far-field. We briefly discuss the effect of nozzle geometry by comparing the flow field in studies that used a blockage disk to those that employed thick inner nozzle lip thickness. Similarities and differences are discussed. While impinging coaxial jets have not been investigated much, we argue in this review that the rich flow dynamics in the near-field of the coaxial jet might be put to an advantage in fine-tuning coaxial jets impinging onto surfaces for specific heat and mass transfer applications. Several open questions are discussed at the end of this review.

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7

Sundaram, Rajkumar, Parthasarathy Vasanthakumar, and Aravindh Kumar Suseela Moorthi. "Experimental Study of Three Stream Coaxial Jets." ECS Transactions 107, no. 1 (April 24, 2022): 1943–49. http://dx.doi.org/10.1149/10701.1943ecst.

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A core Mach 2 jet from the convergent-divergent nozzle in the presence of two coaxial sonic streams from convergent nozzles was investigated experimentally at different nozzle pressure ratios using visualization technique. The jet field was visualized using shadowgraph for nozzle pressure ratio (NPR) 3 to 6. From the visualization results, it was observed that the core length of Mach 2 jet for NPRs 3 to 6 increased with increasing coflow NPRs, indicating reduced mixing of coflow three stream jets as compared to Mach 2 jet (without coflows). From the present study, it was clear that the use of two sonic coflows on Mach 2 jet would result in core elongation for all the NPRs thus acting as a mixing inhibitor. But the sonic coflows were found to weaken the waves in Mach 2 jet, which is advantageous from the aeroacoustic point of view.

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8

Knowles, K., and L. Kirkham. "Inverted-profile coaxial jet flows relevant to Astovl applications." Aeronautical Journal 102, no. 1017 (September 1998): 377–84. http://dx.doi.org/10.1017/s0001924000065155.

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AbstractAn experimental investigation has been performed into the free jet and wall jet characteristics of high pressure ratio coaxial jets operating with inverted velocity profiles and impinging onto a ground plane. Pitot-static probes have been used to record free jet properties at various distances from the jet exit plane, and wall jet properties of the impinging jets at various radial positions. Jet properties such as velocity decay and spreading rates were calculated and compared to published literature. Wall jet development was investigated and recorded. Inner and outer nozzle pressure ratio (NPR) were altered to give a range of jet exit conditions. The results obtained showed variations in the wall jet properties as jet exit conditions were altered, but wall jet self-similarity was found and varying either nozzle height above the ground plane or NPR did not alter this. Free jet data showed large variations in behaviour with changes in NPR. The inverted profile jets behaved similarly to annular jets, showing similar characteristics. Inner jet pressurisation was observed for inverted profile jets and also significant acceleration of the flow from the inner, lower NPR, jet when this was subcritical.

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9

Motoaki, Kimura, Asakura Jun, Onishi Masazumi, Sayo Kentaro, and Miyagi Norimasa. "1044 JET DIFFUSION CONTROL USING A COAXIAL DBD PLASMA ACTUATOR." Proceedings of the International Conference on Jets, Wakes and Separated Flows (ICJWSF) 2013.4 (2013): _1044–1_—_1044–6_. http://dx.doi.org/10.1299/jsmeicjwsf.2013.4._1044-1_.

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10

Belkacem, Safer Nabil, and Abedelhadi Beghidja. "Numerical Investigation of Coaxial Turbulent Jet." International Review of Mechanical Engineering (IREME) 13, no. 2 (February 28, 2019): 78. http://dx.doi.org/10.15866/ireme.v13i2.16668.

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11

Burattini, P., and A. Talamelli. "Acoustic control of a coaxial jet." Journal of Turbulence 8 (January 2007): N47. http://dx.doi.org/10.1080/14685240701660438.

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12

Wang, Dazhi, Xiaojun Zhao, Yigao Lin, Junsheng Liang, Tongqun Ren, Zhenghao Liu, and Jiangyu Li. "Nanoscale coaxial focused electrohydrodynamic jet printing." Nanoscale 10, no. 21 (2018): 9867–79. http://dx.doi.org/10.1039/c8nr01001c.

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13

BEHROUZI, Parviz, and James J. McGUIRK. "Experimental Studies of Coaxial Jet Flows." Journal of Fluid Science and Technology 2, no. 2 (2007): 346–58. http://dx.doi.org/10.1299/jfst.2.346.

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14

Liu, Kun, De-jun Sun, and Xie-yuan Yin. "Instability of Gas/Liquid Coaxial Jet." Journal of Hydrodynamics 19, no. 5 (October 2007): 542–50. http://dx.doi.org/10.1016/s1001-6058(07)60151-6.

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15

Kozlov, V. V., G. R. Grek, M. V. Litvinenko, Yu A. Litvinenko, A. S. Tambovzev, and A. G. Shmakov. "Hydrogen Micro Jet Diffusion Combustion in a Coaxial Air Jet." Doklady Physics 66, no. 1 (January 2021): 1–4. http://dx.doi.org/10.1134/s1028335820110051.

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16

Dellenback, P. A., J. L. Sanger, and D. E. Metzger. "Heat Transfer in Coaxial Jet Mixing With Swirled Inner Jet." Journal of Heat Transfer 116, no. 4 (November 1, 1994): 864–70. http://dx.doi.org/10.1115/1.2911460.

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Convective heat transfer data are presented for coaxial jet mixing in a constant-diameter tube. The inner jet diameter was approximately twice the annular gap dimension. Water, with a nominal inlet Prandtl number of 6, was used as the working fluid. For the inner jet, Reynolds numbers of 30,000 and 100,000 were examined and the swirl number was varied from zero to one. Annular flow rates were characterized by a ratio of annular-to-inner jet axial momentum, which was varied from 0 to 8.3. In all cases the annular jet was unswirled. Plots of local Nusselt numbers show minima and maxima corresponding to the separation and reattachment associated with wall-bounded recirculation. As inner jet swirl strength increased from zero to its maximum value, the location of peak Nusselt number shifted upstream. Local Nusselt numbers achieved magnitudes as high as 9.7 times fully developed values for cases with high swirl and low annular flow rate. As the annular jet’s flow rate was increased, the heat transfer enhancement decreased while the near-wall recirculation zones were stretched and shifted downstream, until at sufficiently high values of the momentum flux ratio, the zones were no longer in evidence from the heat transfer data.

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17

Liu, Haifeng, Wenguang Cao, Jianliang Xu, Weifeng Li, and Zhigang Sun. "Dispersion mode of granular jet in a coaxial air jet." Powder Technology 217 (February 2012): 566–73. http://dx.doi.org/10.1016/j.powtec.2011.11.022.

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18

Vempati, Bhadraiah, Mahesh V. Panchagnula, Alparslan Öztekin, and Sudhakar Neti. "Numerical Investigation of Liquid-Liquid Coaxial Flows." Journal of Fluids Engineering 129, no. 6 (December 8, 2006): 713–19. http://dx.doi.org/10.1115/1.2734223.

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This paper presents numerical results of the interfacial dynamics of axisymmetric liquid-liquid flows when the denser liquid is injected with a parabolic inlet velocity profile into a coflowing lighter fluid. The flow dynamics are studied as a function of the individual phase Reynolds numbers, viscosity ratio, velocity ratio, Bond number, and capillary number. Unsteady, axisymmetric flows of two immiscible fluids have been studied using commercial software, FLUENT® with the combination of volume of fluid (VOF) and continuous surface force (CSF) methods. The flows have been categorized as “flow-accelerated regime (FAR) and “flow-decelerated regime” (FDR) based on acceleration/deceleration of the injected fluid. The injected jet diameter decreases when the average inlet velocity ratio is less than unity. The outer fluid velocity has a significant effect on the shape and evolution of the jet as it progresses downstream. As the outer liquid flow rate is increased, the intact jet length is stretched to longer lengths while the jet radius is reduced due to interfacial stresses. The jet radius appears to increase with increasing viscosity ratio and ratio of Bond and capillary numbers. The results of numerical simulations using FLUENT agree well with experimental measurements and the far-field self-similar solution.

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19

Panda, Samarendra, Trushar B. Gohil, and Venugopal Arumuru. "Influence of mass flux ratio on the evolution of coaxial synthetic jet." Physics of Fluids 34, no. 9 (September 2022): 093601. http://dx.doi.org/10.1063/5.0101727.

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This paper highlights a direct numerical simulation study on the flow field of a coaxial synthetic jet (CSJ) generated from two independently controlled synthetic jet actuators, which are combined coaxially with [Formula: see text] orientation angle. The jet is issued into a quiescent environment from inner and annular openings (orifices) with equal hydraulic diameters, employing an oscillating boundary. Seven different mass flux ratios ([Formula: see text]) such as [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] are considered for the study. The average velocity ([Formula: see text]) of inner jet, measured at orifice exit, is kept at [Formula: see text] m/s (Reynolds number, [Formula: see text]), and the same is varied for the annular jet to achieve the desired [Formula: see text] s. The influence of [Formula: see text] s on the vortex rings, evolved from inner and annular orifices, along with their dynamics, is predicted by furnishing the instantaneous flow field. Also, we examine the effect of [Formula: see text] s on the mean flow parameters of the CSJ. Moreover, the CSJ flow field is compared with the inner cavity synthetic jet (SJ), and annular cavity SJ under identical conditions, to demonstrate the superior performance of the CSJ over the single cavity SJs. For CSJ, the azimuthal instability of the evolved vortex rings can be triggered by decreasing the [Formula: see text], which results in a wide jet. For [Formula: see text], the CSJ retains its axisymmetric nature, and the interaction of vortex rings emanating from the inner and annular cavities influences the strength and spreading of the CSJ. The modal decomposition of the instantaneous flow field is also performed using proper orthogonal decomposition method to gain insight of the coherent vortical structures present in the modes. The study will be useful for deploying such novel coaxial synthetic jets in various applications.

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20

Kumar, Abhijeet, and Srikrishna Sahu. "Liquid jet breakup unsteadiness in a coaxial air-blast atomizer." International Journal of Spray and Combustion Dynamics 10, no. 3 (March 22, 2018): 211–30. http://dx.doi.org/10.1177/1756827718760905.

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The aim of this paper is to experimentally characterize the liquid jet breakup unsteadiness in a coaxial air-blast atomizer. The current research focuses on the measurement of the fluctuations of the jet breakup length and the flapping instability of the liquid jet, which contribute to the downstream fluctuations of the spray characteristics. The optical connectivity technique was used to measure the instantaneous breakup length of the water jet. Also, time resolved shadowgraph images of the primary jet breakup process were captured by high-speed imaging to characterize the jet instabilities at different axial locations from the atomizer exit. Experiments were performed for a wide range of air-to-liquid momentum flux ratio ( M) and aerodynamic Weber number ( Weg) corresponding to membrane- and/or fiber breakup mode of the jet disintegration process. The mean jet breakup length was found to vary inversely with M through a power law relation in agreement with the literature, while the breakup length fluctuations were found to first decrease and then increase with M. In order to capture the unsteady dynamics of the jet breakup process, the proper orthogonal decomposition analysis of the optical connectivity images was performed. The jet flapping and the fluctuations of the jet breakup length were identified as the second and the third spatial proper orthogonal decomposition modes, respectively, for all operating conditions of the atomizer. The amplitude and the frequency of the instabilities were measured by temporal tracking of the liquid–air interface on the shadowgraph images. The disturbance close to the injector exit corresponds to the Kelvin–Helmholtz instability, while close to the jet breakup point the jet exhibits the flapping instability, which is characterized by lateral oscillation of the jet about the atomizer axis. The influence of the liquid jet Reynolds number and momentum flux ratio on the KH and the flapping instabilities are examined.

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21

Kiwata, Takahiro, Takashi Ishii, Shigeo Kimura, and Atsushi Okajima. "Flow Visualization and Characteristics of a Tabbed Coaxial Jet(Special Nozzle)." Proceedings of the International Conference on Jets, Wakes and Separated Flows (ICJWSF) 2005 (2005): 197–202. http://dx.doi.org/10.1299/jsmeicjwsf.2005.197.

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22

Perumal, Arun Kumar, Himanshu Singh, and Ethirajan Rathakrishnan. "Passive control of coaxial jet with supersonic primary jet and sonic secondary jet." Physics of Fluids 32, no. 7 (July 1, 2020): 076101. http://dx.doi.org/10.1063/5.0012468.

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23

Sureshkumar, A., and BTN Sridhar. "Axial flow development characteristics of circular and triangular supersonic jets in the presence of an annular coflow at large separation distance." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 234, no. 3 (November 13, 2019): 804–17. http://dx.doi.org/10.1177/0954410019887631.

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Experimental studies were conducted to assess the effect of an annular coflow which surrounded a supersonic core jet in a coaxial jet system. Two different core jet shapes were employed which were circular and equilateral triangular. The core jets were maintained at two different total pressures, i.e. 360 and 550 kPa which corresponded to overexpansion conditions. The effect of coflow which surrounded core jet at a distance larger than the core jet diameter was such that the supersonic core length of the core jet was reduced in contrast to the elongation which was reported by earlier researchers for closer distances between the two jets. The Schlieren images of the coaxial jet system had shown that the region between the jet boundary of core jet and inner boundary of the annular coflow had a strong interaction with core jet which was characterised by a wave system and vortices. This region caused a reduction in supersonic core length and weakening of shock structure in the core jet. These findings have been corroborated by total pressure measurements along the core jet centreline. For the same operational conditions, the coflow caused reduction in supersonic core length more for triangular core jet when compared to that for circular core jet.

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24

Karthikeyan, N., and B. T. N. Sridhar. "Numerical and Experimental Studies on the Supersonic Coaxial Jet Mixing." Advanced Materials Research 354-355 (October 2011): 691–95. http://dx.doi.org/10.4028/www.scientific.net/amr.354-355.691.

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Coaxial nozzles are an integral part of many engineering systems where mixing of different fluid streams is required. Single noncircular nozzles have been shown to have better mixing characteristics than their axisymmetric counterparts. Therefore, a combination of such nozzles into coaxial configurations is promising. The aim of the present study is to quantitatively determine the effects of the geometry of the primary supersonic jet on the mixing characteristics with the secondary high speed subsonic jet. Measurements of pressure profiles at several positions along central axis of jets using identical facilities and nominally identical experimental conditions were done. The mixing is dominated by the vortex structures that are present in the inner shear layers. The interaction of the vortex structures govern the growth, and entrainment, and mixing of the jet. Also, the experimental results show that the radial and centerline pressure profiles through various coaxial jets has good correlation with the CFD simulation.

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25

Tambovtsev, A. S., G. R. Grek, V. V. Kozlov, M. V. Litvinenko, Yu A. Litvinenko, and A. G. Shmakov. "Air Round Microjet Interaction with Coaxial Air Jet for Supersonic Speed Jets Efflux." Siberian Journal of Physics 14, no. 3 (2019): 39–52. http://dx.doi.org/10.25205/2541-9447-2019-14-3-39-52.

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Results of experimental studies of the round hydrogen microjet interaction with a coaxial air for supersonic speed jets efflux are presented in this work. It is shown that interaction of round and coaxial air jets at their supersonic efflux leads to appearance of a train small/large-scale and, on the contrary, large/small-scale supersonic cells on a resultant jet with growth and reduction of speed of its efflux, respectively. It is found that the result of the round and coaxial air jets interaction at their supersonic efflux does not depend on geometrical parameters of a round and coaxial exit nozzle.

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26

Ströher, G. R., C. A. Martins, and C. R. De Andrade. "NUMERICAL AND EXPERIMENTAL STUDY OF A FREE INCOMPRESSIBLE ISOTHERMAL TURBULENT COAXIAL JET." Revista de Engenharia Térmica 9, no. 1-2 (December 31, 2010): 98. http://dx.doi.org/10.5380/reterm.v9i1-2.61939.

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In the present study the free incompressible isothermal turbulent coaxial jet problem is numerically solved, and compared with experimental measurements for different velocity ratio between the inner and the outer streams of the jet. The radial profile of the axial mean velocity was obtained with hot anemometry at different axial positions. Governing equations (mass conservation, momentum, turbulence model) were discretized employing the finite volume method with a segregated solver. The analysis of the experimental results showed that coaxial jet flow fields did not present self-similarity up to z/D=25, and the numerical solution using the Shih’s k ε turbulence model did not match reasonably with the experimental data, with a difference of about ± 10%.

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27

REHAB, H., E. VILLERMAUX, and E. J. HOPFINGER. "Flow regimes of large-velocity-ratio coaxial jets." Journal of Fluid Mechanics 345 (August 25, 1997): 357–81. http://dx.doi.org/10.1017/s002211209700637x.

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An investigation of the near-field flow structure of coaxial jets with large outer to inner velocity ratio ru has been conducted. Since in all cases ru>1, the outer jet dominates the near-field flow structure. Two flow regimes are identified depending on whether ru is larger or smaller than a critical value ruc. When ru<ruc, the fast annular jet periodically pinches the central, slow jet near the end of the inner potential cone. The pinching frequency corresponds to the outer-jet mode. The length of the inner potential cone is strongly dependent on ru and behaves like A/ru, where A depends weakly on the initial conditions. When ru>ruc, the inner potential cone is truncated and is followed by an unsteady recirculation bubble with low-frequency oscillation.The transition from one regime to another is explained by a simple model whose ingredients are the turbulent entrainment rate, governed by the outer-jet mixing layers and mass conservation. This model satisfactorily predicts the dependence of the inner potential cone length on ru and the critical velocity ratio ruc. The recirculation bubble has a wake-type instability. It oscillates at a low frequency and a large amplitude compared to the Kelvin–Helmholtz mode. Angular cross-correlations in the plane parallel to the jet outlet show moreover that this oscillation displays an azimuthal precession such that the rotation time of the phase of the oscillation equals the oscillation period. These salient features are discussed in the framework of the nonlinear delayed saturation (NLDS) model.

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28

Carvalho, Isabel S., and Norman Toy. "VORTEX BREAKDOWN OF UNCONFINED COAXIAL JET FLOWS." Journal of Flow Visualization and Image Processing 7, no. 4 (2000): 18. http://dx.doi.org/10.1615/jflowvisimageproc.v7.i4.20.

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29

Sanger, J. L., and P. A. Dellenback. "Heat Transfer in Counterswirled Coaxial Jet Mixing." Journal of Propulsion and Power 14, no. 3 (May 1998): 384–91. http://dx.doi.org/10.2514/2.5291.

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30

Nallasamy, M. "Computation of confined turbulent coaxial jet flows." Journal of Propulsion and Power 3, no. 3 (May 1987): 263–68. http://dx.doi.org/10.2514/3.22983.

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31

Sivakumar, D., and B. N. Raghunandan. "Jet Interaction in Liquid-Liquid Coaxial Injectors." Journal of Fluids Engineering 118, no. 2 (June 1, 1996): 329–34. http://dx.doi.org/10.1115/1.2817381.

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Interaction between two conical sheets of liquid formed by a coaxial swirl injector has been studied using water in the annular orifice and potassium permanganate solution in the inner orifice. Experiments using photographic techniques have been conducted to study the influence of the inner jet on outer conical sheet spray characteristics such as spray cone angle and break-up length. The core spray has a strong influence on the outer sheet when the pressure drop in the latter is low. This is attributed to the pressure variations caused by ejector effects. This paper also discusses the merging and separation behavior of the liquid sheets which exhibits hysteresis effect while injector pressure drop is varied.

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32

Voronin, A. V., V. Yu Goryainov, and V. K. Gusev. "Investigation of a Coaxial Plasma Jet Accelerator." Technical Physics 65, no. 6 (June 2020): 987–93. http://dx.doi.org/10.1134/s1063784220060286.

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33

Zhdanov, Valery, and Egon Hassel. "Mixing Enhancement in a Coaxial Jet Mixer." Advances in Materials Physics and Chemistry 02, no. 04 (2012): 134–37. http://dx.doi.org/10.4236/ampc.2012.24b035.

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34

Inan, A. T., M. Z. Gul, and M. O. Isikan. "Coaxial Circular Jet Flows with Conical Attachments." Acta Physica Polonica A 127, no. 4 (April 2015): 1373–79. http://dx.doi.org/10.12693/aphyspola.127.1373.

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35

YAMATO, Yuta, and Daisuke WATANABE. "Effect of helical modes on jet diffusion in a coaxial jet." Proceedings of Conference of Hokuriku-Shinetsu Branch 2018.55 (2018): E031. http://dx.doi.org/10.1299/jsmehs.2018.55.e031.

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36

Guo, Li-Mei, Ming Lü, and Zhi Ning. "Stability of a Viscous Liquid Jet in a Coaxial Twisting Compressible Airflow." Processes 9, no. 6 (May 24, 2021): 918. http://dx.doi.org/10.3390/pr9060918.

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Based on the linear stability analysis, a mathematical model for the stability of a viscous liquid jet in a coaxial twisting compressible airflow has been developed. It takes into account the twist and compressibility of the surrounding airflow, the viscosity of the liquid jet, and the cavitation bubbles within the liquid jet. Then, the effects of aerodynamics caused by the gas–liquid velocity difference on the jet stability are analyzed. The results show that under the airflow ejecting effect, the jet instability decreases first and then increases with the increase of the airflow axial velocity. When the gas–liquid velocity ratio A = 1, the jet is the most stable. When the gas–liquid velocity ratio A > 2, this is meaningful for the jet breakup compared with A = 0 (no air axial velocity). When the surrounding airflow swirls, the airflow rotation strength E will change the jet dominant mode. E has a stabilizing effect on the liquid jet under the axisymmetric mode, while E is conducive to jet instability under the asymmetry mode. The maximum disturbance growth rate of the liquid jet also decreases first and then increases with the increase of E. The liquid jet is the most stable when E = 0.65, and the jet starts to become more easier to breakup when E = 0.8425 compared with E = 0 (no swirling air). When the surrounding airflow twists (air moves in both axial and circumferential directions), given the axial velocity to change the circumferential velocity of the surrounding airflow, it is not conducive to the jet breakup, regardless of the axisymmetric disturbance or asymmetry disturbance.

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37

Saravanan, G., A. Vinoth Kumar, and K. B. Ravichandrakumar. "Numerical Analysis of Subsonic Coaxial Jet on Effect of Potential Core Length." Journal of Advances in Mechanical Engineering and Science 2, no. 1 (February 26, 2016): 26–32. http://dx.doi.org/10.18831/james.in/2016011003.

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38

Mergheni, Ali, Toufik Boushaki, Jean-Charles Sautet, Gille Godard, Ticha Ben, and Nasrallah Ben. "Effects of different mean velocity ratios on dynamics characteristics of a coaxial jet." Thermal Science 12, no. 2 (2008): 49–58. http://dx.doi.org/10.2298/tsci0802049m.

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The flow field of a coaxial jet configuration having inner and outer diameter ratio Di /Do = 0.33 is studied for four values of the velocity ratios and m = Ui /Uo = 5.17, 1.13, 0.77, and 0.54. The profiles of the mean axial velocity, of the axial turbulence intensities, and of the shear stress are described for the initial and fully zones. The obtained results show the inner potential core length of the coaxial jet strongly depends on the velocity ratio while the outer potential core for jets having velocity ratios greater than unity seems to be insensitive to the velocity ratio. As expected, the inner jet core length is seen to decrease with decreasing velocity ratio; jets with velocity less than unity develop faster than those with m greater than unity and the Reynolds stress show a zero-crossing in the near-region. .

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39

Hsu, M. J., and P. A. Molian. "Off-Axial, Gas-Jet-Assisted, Laser Cutting of 6.35-mm Thick Stainless Steel." Journal of Engineering for Industry 117, no. 2 (May 1, 1995): 272–76. http://dx.doi.org/10.1115/1.2803314.

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A dual gas-jet, laser-cutting technique involving coaxial and off-axial oxygen gas flows was developed to cut 6.35-mm thick AISI 304 stainless steel plates with a 1.2-kW CO2 gas transport laser at a cutting speed of 12.7 mm/sec (30 in./min). Under identical process conditions, the single, coaxial gas jet could not cut the stainless steel although the cutting speed was reduced to 2.11 mm/sec (5 in./min). Thresholds of off-axial nozzle diameter, gas-impinging angle, oxygen pressure, and other process parameters were determined to obtain clean-cut edge quality (average dross height 0.25 mm). Experimental data coupled with a fluid-dynamics model of gas flow were presented to show the effectiveness of the dual gas-jet, laser-cutting method in achieving the maximum machining rate without deteriorating the quality of cut.

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40

Semykin, S. I., T. S. Golub, S. A. Dudchenko, and V. V. Vakulchuk. "High-temperature study of the features of metal blowing in the converter through the top oxygen lance with an annular slit nozzle." Fundamental and applied problems of ferrous metallurgy, no. 32 (2018): 229–37. http://dx.doi.org/10.52150/2522-9117-2018-32-229-237.

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The aim of the work is to study on the physical model of an oxygen converter the interaction of an oxygen jet flowing from a coaxial slotted nozzle with an iron-carbon melt. During cold modeling of the blowdown, it was found that the gas jet flowing out of the nozzle along the propagation axis has a large dynamic pressure compared to the cylindrical nozzle, as a result of which it penetrates deeper into the liquid. Comparative analysis of video materials obtained during high-temperature melting revealed gas-dynamic differences in the nature of the interaction of the jet from the coaxial slit nozzle with the surface of the melt, especially at the beginning of the melt blowing, when the slag emulsion was not yet formed. Comparison of the results of high-temperature modeling of the interaction of the oxygen jet flowing from the coaxial slit nozzle with the metal melt when compared with the work of the four-nozzle tip showed that earlier ignition of the heat was observed, active absorption of lime and visually more rigid character of the blowdown with the formation of a smaller amount of slag than in the comparative melts. The conclusions obtained at the «cold» modeling stage were confirmed on a higher dynamic head and deep penetration into the jet melt using an experienced tip. It is revealed that the use of an experienced tip contributes to a greater heating of the bath and a reduction in the level of dust.

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41

Ryu, Myung-Ho, and Seul-Hyun Park. "Ignitability of Jet A1 Oxygen Co-axial Diffusion Flames Diluted with Inert Gases." Fire Science and Engineering 36, no. 6 (December 31, 2022): 1–7. http://dx.doi.org/10.7731/kifse.adea1f23.

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In this study, the ignitability characteristics affected by an oxygen coaxial flow diluted with inert gases (nitrogen and helium) were experimentally investigated using Jet A1 oxygen diffusion flame configurations. As the molar concentration of oxygen supplied to the coaxial flow increased, the dilution of the inert gas decreased, which drastically lowered the measured minimum ignition energy. When only oxygen gas was supplied to the coaxial flow without dilution with the inert gas, ignition was most easily observed, thereby widening the ignition range. With a constant oxygen-inert co-flow rate, the ignition suppressibility under helium dilution was superior to that under nitrogen dilution as the molar concentration of oxygen decreased.

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42

Hopfinger, E. J., and J. C. Lasheras. "Explosive breakup of a liquid jet by a swirling coaxial gas jet." Physics of Fluids 8, no. 7 (July 1996): 1696–98. http://dx.doi.org/10.1063/1.868981.

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43

KOSO, Toru, Mamoru SHIRAISHI, and Taisuke NAKAMURA. "Effect of a Coaxial annular Synthetic Jet on a Circular Jet Flow." Proceedings of the Fluids engineering conference 2004 (2004): 238. http://dx.doi.org/10.1299/jsmefed.2004.238.

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44

Wang, Bingchuan, Wanshun Li, Bide Zhang, Kai Liu, Ping Peng, Disheng Wang, Rongqiu Luo, Jin Zhang, Jing Feng, and Haining Yu. "Numerical study of discharge characteristics of an atmospheric pressure plasma jet with a coaxial dual-channel inlet." Journal of Applied Physics 131, no. 11 (March 21, 2022): 113303. http://dx.doi.org/10.1063/5.0073577.

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A two-dimensional axisymmetric fluid model was applied to investigate the influence of N2 flow velocity on the discharge characteristics of a He plasma jet with a coaxial dual-channel inlet. Helium working gas flowed in the annular space of a coaxial tube and N2 flowed in a central stainless steel tube powered by a DC voltage. When N2 flow velocity increases from 0 m/s, the jet appears to be stratified, forming the outer side and inner side of the jet, and the electron density on the outside of the jet is much higher than that on the inside. For different N2 flow velocities, the peak densities of He+ and N2(c3π) appear in the jet head, while the peak densities of He* and N2+ both appear at the dielectric nozzle and the jet head. When N2 flow velocity is low, the Penning ionization rate is lower than the electron impact ionization rate, but when N2 flow velocity is high, it is just the opposite, which can increase the concentration of reactive species and contribute to the practical application of the jet. N2 flow velocity not only changes the length and structure of the jet but also controls the uniformity of the distribution of reactive species in the jet, which indicates that there is an optimal N2 flow velocity to make the jet longer and more uniform in space, which will greatly promote the practicality and flexibility of the plasma jet and also provide meaningful insights for optimizing and controlling the characteristics of the plasma jet.

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45

Gabuzda, Denise C., Matt Nagle, and Naomi Roche. "The jets of AGN as giant coaxial cables." Astronomy & Astrophysics 612 (April 2018): A67. http://dx.doi.org/10.1051/0004-6361/201732136.

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Context. The currents carried by the jets of active galactic nuclei (AGNs) can be probed using maps of the Faraday rotation measure (RM), since a jet current will be accompanied by a toroidal magnetic field, which will give rise to a systematic change in the RM across the jet. Aims. The aim of this study is to identify new AGNs displaying statistically significant transverse RM gradients across their parsec-scale jets, in order to determine how often helical magnetic fields occur in AGN jets, and to look for overall patterns in the implied directions for the toroidal field components and jet currents. Methods. We have carried out new analyses of Faraday RM maps derived from previously published 8.1, 8.4, 12.1 and 15.3 GHz data obtained in 2006 on the NRAO Very Long Baseline Array (VLBA). In a number of key ways, our procedures were identical to those of the original authors, but the new imaging and analysis differs from the original methods in several ways: the technique used to match the resolutions at the different frequencies, limits on the widths spanned by the RM gradients analyzed, treatment of core-region RM gradients, approach to estimation of the significances of the gradients analyzed, and inclusion of a supplementary analysis using circular beams with areas equal to those of the corresponding elliptical naturally weighted beams. Results. This new analysis has substantially increased the number of AGNs known to display transverse RM gradients that may reflect the presence of a toroidal magnetic-field component. The collected data on parsec and kiloparsec scales indicate that the current typically flows inward along the jet axis and outward in a more extended region surrounding the jet, typical to the current structure of a co-axial cable, accompanied by a self-consistent system of nested helical magnetic fields, whose toroidal components give rise to the observed transverse Faraday rotation gradients. Conclusions. The new results presented here make it possible for the first time to conclusively demonstrate the existence of a preferred direction for the toroidal magnetic-field components – and therefore of the currents – of AGN jets. Discerning the origin of this current-field system is of cardinal importance for understanding the physical mechanisms leading to the formation of the intrinsic jet magnetic field, which likely plays an important role in the propagation and collimation of the jets; one possibility is the action of a “cosmic battery”.

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46

Lü, Ming, and Zhi Ning. "On the thermal instability of supercavitating liquid jet surrounded by coaxial rotary gas." Journal of Mechanics 37 (2021): 551–65. http://dx.doi.org/10.1093/jom/ufab024.

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Abstract Based on the jet stability theory, under the conditions of gas rotation, fluid compressibility and supercavitation, this paper gives the mathematical model describing the thermal instability of supercavitating liquid jet surrounded by a coaxial rotary gas, and the corresponding numerical method for solving the mathematical model is proposed and verified by the data in reference. Then, this paper analyzes the effects of gas–liquid temperature differences and temperature gradients on jet instability, and studies the thermal stability of supercavitating jet. The results show that the maximum disturbance growth rate, the dominant frequency and the maximum disturbance wave numbers increase linearly with the increase of gas–liquid temperature differences. The existence of temperature gradient inside the jet makes the effects of temperature differences on jet instability more obvious. The temperature gradient will inhibit the effect of supercavitation on jet instability, while gas–liquid temperature difference will promote the effect of supercavitation on jet instability.

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47

Poláček, Josef, Irena Marie Hlaváčová, and Martin Tyč. "A Short Note about the Impact Action of a Water Jet Stabilized by a Coaxial Air Stream in the Air and Underwater." Materials 14, no. 17 (September 2, 2021): 5015. http://dx.doi.org/10.3390/ma14175015.

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A new original method, applying a coaxial protective airflow, was tested aiming to improve the pure water jet efficiency in surface layer removal or medium hard materials cutting or blasting. The dual action of the air flow is expected: the air co-flowing the water jet with approximately the same velocity should prevent the central jet from breaking up into tiny droplets in the near field, and simultaneously, it should support jet decomposition into big parts with enough destructive potential in the far-field. A brief survey of the relevant literature dealing with the water jet instability is presented, introducing four recognized breakup regimes. An original cutting head designed to generate a waterjet surrounded by protective coaxial air flow is introduced. The submitted device is supposed to operate within the first wind-induced regime. Two types of experiments, consisting of blasting limestone bricks placed either in the air or underwater, were realized. The depths of kerfs produced with different water pressures and air overpressures were evaluated. While no substantial positive effect was recognized in the air performance, the submerged blasting of the same material under similar conditions appeared to be promising.

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48

Dinesh, K. K. J. Ranga, A. M. Savill, K. P. Garry, J. C. Holt, D. I. A. Poll, and M. P. Kirkpatrick. "Modelling of Coaxial Jet Efflux Mixing using LES." International Journal of Fluid Mechanics Research 39, no. 1 (2012): 20–39. http://dx.doi.org/10.1615/interjfluidmechres.v39.i1.20.

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49

Broučková, Z., Z. Trávníček, and P. Šafařík. "Active control of the jet in coaxial arrangement." EPJ Web of Conferences 45 (2013): 01016. http://dx.doi.org/10.1051/epjconf/20134501016.

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50

Candel, S., G. Herding, R. Synder, P. Scouflaire, C. Rolon, L. Vingert, M. Habiballah, et al. "Experimental Investigation of Shear Coaxial Cryogenic Jet Flames." Journal of Propulsion and Power 14, no. 5 (September 1998): 826–34. http://dx.doi.org/10.2514/2.5346.

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